"Earliest instance" refers to the very first occurrence or example of something. It represents the beginning or the initial time when something happened or was observed. Full definition
And sure enough, I could find earlier instances of its use across the last decade. (slaw.ca)
However, in earlier instances the bitcoin exchanges in the country had assured that they have rules and regulations in place to check money laundering or other illegal activities. (qz.com)
But perhaps one of the most significant early instances of its use — at least for understanding what the phrase originally meant — comes just over a decade earlier. (firstthings.com)